Phosphine-Catalyzed alpha- and Vicinal Bis-Addition of P(O)H Compounds to Alkynoates

The efficient route to phosphine-catalyzed preparation of alpha-phosphoryl acrylates and vicinal bis-phosphoryl propanoates was developed. The products of diarylphosphine oxide monoaddition and dibenzyl-H-phosphonate vicinal bis-addition to ethylphenylpropiolate were obtained by using previously data on the reactivity and prototropic tautomerism of various classes of P(O)H compounds. In previous works devoted to the phosphine-catalyzed addition of P(O)H compounds to this activated alkyne, the use of secondary phosphine oxides gave only vicinal bisphosphine oxides, while the addition of H-phosphonates led only to alpha-products. On the basis of this work and our previous studies, a series of the reactivity increase of P(O)H compounds in the phosphine-catalyzed beta-addition reaction can be assumed: (AlkO)(2)P(O)H <= Ph(EtO)P(O)H <(BnO)(2)P(O)H <(m-(CH3)(2)C6H3)(2)P(O)H2P(O)H2P(O)H. The alpha-umpolung addition is less dependent on nature of P(O)H compounds. The increased reactivity of Ph2P(O)H can be used for the introduction of several groups at once: phosphonate and phosphine oxide at the multiple bond of alkyne with or without the isolation of the alpha-addition intermediate.